Equine idiopathic cheek teeth fractures: Part 2: A practice-based survey of 147 affected horses in Britain and Ireland

Fracture Resistance of Equine Cheek Teeth With and Without Occlusal Fissures: A Standardized ex vivo Model

Background:Ex vivo fracture models are frequently used in human dentistry to provide insights in the fracture mechanisms of teeth. Equine cheek teeth fractures are an important dental pathology, but there has been no research performed to examine the fracture resistance ex vivo.

Objective: To evaluate the fracture resistance of equine cheek teeth and identify anatomical predictors that might influence fracture resistance in healthy teeth. It was further evaluated if the presence of a fissure caused a decrease in fracture resistance.

Study design:Ex vivo experimental design.

Methods: Individual cheek teeth were subjected to a compression load in a universal testing machine until fracture occurred. Testing was performed in two study groups. A first group of healthy cheek teeth was tested to examine anatomical predictors on fracture resistance. A second group comprised cheek teeth with occlusal fissures and an equal number of age- and size-matched fissure-free teeth as controls. The effect of possible predictors on fracture resistance was investigated by regression analysis.

Results: In the first group, fracture resistance was significantly influenced by the location on the tooth where testing was performed in both maxillary (p < 0.001) and mandibular teeth (p < 0.001). Additional significantly associated factors were Triadan number in mandibular (p = 0.009) and the mesiodistal length of the occlusal surface of maxillary teeth (p = 0.01). Experimentally induced crown fractures that extended below the simulated bone level were more frequently associated with pulp horn exposure (p < 0.001). In the second group, significant lower fracture loads were recorded in teeth with fissures (mandibular p = 0.006; maxillary p < 0.001), compared to fissure-free teeth.

Main limitations: This ex vivo model does not imitate the in vivo masticatory forces and lacks the shock-absorbing properties of the periodontal ligament.

Conclusions: The methodology used in this study provides an ex vivo experimental set-up to test fracture resistance of equine cheek teeth enabling evidence-based research to examine the potentially weakening effects of tooth pathology and its treatments. Crown resistance to fracture differed along the occlusal surface of healthy equine cheek teeth, and the presence of fissures further decreased fracture resistance.

A computed tomographic study of endodontic and apical changes in 81 equine cheek teeth with sagittal fractures

BACKGROUND

Sagittal fractures of equine cheek teeth are commonly observed during oral examination. There are few reports on the apical and endodontic pathology associated with such fractures seen during computed tomographic (CT) examination.

OBJECTIVES

This study aimed to document the prevalence of CT changes indicative of apical disease in equine cheek teeth, which have suffered a sagittal fracture involving the clinical ± reserve crown.

STUDY DESIGN

This study is a retrospective case series.

METHODS

CT examinations of equine heads with sagittal fractures of cheek teeth present were reviewed: 81 teeth from 49 horses were identified to have a sagittal cheek tooth fracture. The images were evaluated for apical pathology including gas (in the endodontic system and periapically), widened periodontal space, periapical sclerosis, apical clubbing, cementoma/hypercementosis, lamina dura loss, associated sinusitis and sinus mucosal swelling. An apical infection grading system was created to give each tooth a score. Hounsfield units were used to measure the density of the endodontic, apical and periapical regions. The fracture length ratio was recorded. Statistical analysis was performed using a generalised estimating equation to evaluate predictors of apical infection and associations between clinical signs and CT abnormalities.

RESULTS

Eighty-seven sagittal fractures (56 buccal, 17 palatal/lingual and 14 midline) from 81 teeth were recorded (74 maxillary and 7 mandibular). Apical infection was diagnosed in 73% (37/51, P = .05) of buccal, 55% (6/11, P = .07) of palatal/lingual, 100% (13/13) of midline, 100% (6/6) of multiple fractures and 96% (23/24, P = .008) of fractures involving infundibula. There was no significant relationship between apical infection and the presence of clinical signs associated with dental pathology (P = .4). There was no significant association between fracture length ratio and apical infection (P = 1.0). Midline sagittal fractures were significantly associated with sinusitis when compared with all other maxillary fractures (odds ratio [OR] 5.92, 95% confidence interval [CI] 1.67-20.83, P = .006). Loss of the lamina dura was not significantly associated with apical infection (P = .5).

MAIN LIMITATIONS

There is a maxillary cheek tooth bias in the data set and the subjective grading system.

CONCLUSIONS

A large proportion of fractured cheek teeth have evidence of apical infection on CT examination and therefore warrant treatment.

Equine "Idiopathic" and Infundibular Caries-Related Cheek Teeth Fractures: A Long-Term Study of 486 Fractured Teeth in 300 Horses

Background: Limited objective information is available on the prevalence of non-traumatic equine cheek teeth fractures, the signalment of affected horses, and the clinical features and treatment of these fractures.

Objectives: This study aims to document patterns of idiopathic and infundibular caries-related cheek teeth fractures in a referral population and evaluate associations between fracture patterns and horse age, Triadan position of affected teeth, clinical signs, and deemed necessity for treatment.

Study Design: A retrospective case review.

Methods: The clinical records at Edinburgh University Veterinary School (2010–2018) were examined for the presence of non-traumatic equine cheek teeth fractures. Variations in the frequencies of different fracture patterns were compared between horse ages, Triadan tooth positions, clinical signs, and deemed necessity for treatment.

Results: Records of 300 horses with 486 non-traumatic cheek teeth fractures including 77% maxillary and 23% mandibular teeth with a mean of 1.6 (range 1–10) fractured teeth/horse were available. Fracture patterns included maxillary first and second pulp horn (“slab”) cheek teeth fractures (n = 171), caries-related infundibular fractures (n = 88), other maxillary teeth fracture patterns (n = 92), mandibular first and second pulp horn (“slab”) fractures (n = 44), other mandibular fracture patterns (n = 62), and complete clinical crown loss (n = 29; including 23 maxillary and 6 mandibular teeth). The median age of affected horses ranged from 11 years with maxillary “slab” fractures to 15 years with infundibular caries-related fractures. Triadan 08–10s were the most commonly (86%) fractured maxillary teeth. The Triadan 08 and 09 positions were the most commonly (64%) fractured mandibular teeth. No clinical signs were noted in horses with 48% of the fractured teeth; oral pain/quidding was recorded with 26%, clinical apical infection with 23%, and bitting/headshaking problems with 6%. Treatments included extraction of 40% fractured teeth, extraction of small/loose fragments (10%), and odontoplasty. Stable remnants of 60% of fractured teeth were left in horses without clinical signs.

Main Limitations: Long-term follow-up information was not available for all cases.

Conclusions: There is increasing recognition of equine non-traumatic cheek teeth fractures, with about half not causing clinical signs. Teeth with apical infection, multiple fractures, or advanced caries require extraction. Other fractured teeth with subclinical endodontic disease may not need exodontia unless they later cause clinical signs.

Occlusal Fissures in Equine Cheek Teeth: A Prospective Longitudinal in vivo Study

Background: It has been suggested that fissures of the occlusal surface of equine cheek teeth may develop into crown fractures. Objectives: To examine the evolution of fissures present on the occlusal surface of cheek teeth. Furthermore, to investigate the presence of a fissure as a risk factor for the development of a subsequent crown fracture. Study Design: Observational longitudinal study. Methods: Bi-annual dental examinations were performed on 36 horses for 3 years. Video-recordings were made to evaluate the evolution of detected fissures. The effect of possible predictors on the development of tooth fractures was investigated by regression analysis. Results: The evolution of 785 fissures (467 type 1a, 271 type 1b, 47 type 2) was recorded. Fissure characteristics were observed to remain unchanged, disappear, become longer, shorter, change in configuration or change in color. Partial crown fractures (22 maxillary, 50 mandibular) were recorded in 52 cheek teeth in 22/36 horses. Fifty-nine of these fractures evolved from previously observed fissures (24 type 1a, 29 type 1b, 6 type 2). All fissure types proved to be a significant risk factor for the development of a crown fracture (p < 0.001), with the highest odds for type 2 fissures (OR = 14.27; 95% CI = 4.88-41.71). Other significant risk factors were the time of follow-up (p < 0.001), mandibular teeth (p < 0.001) and the lingual side of a tooth (p < 0.001). All fractures were non-complicated. Main Limitations: Some horses were prematurely lost for follow-up, which perhaps influenced the results. A longer follow-up period would have also allowed an evaluation of the risk for pulp disease on the long term subsequent to partial crown fractures. Conclusions: The presence of a fissure of any type, mandibular cheek teeth, the lingual side of cheek teeth, and time of follow-up proved to be significant risk factors for development of a cheek tooth crown fracture. Type 2 fissures showed the highest odds followed by type 1b fissures. The observed partial crown fractures demonstrated a low clinical impact whereby no tooth showed signs of development of endodontal disease.

Assessment of clinical and computed tomographic findings for association with the outcome of intraoral cheek tooth extraction in horses and ponies

OBJECTIVE

To describe clinical and CT findings for horses and ponies undergoing intraoral cheek tooth extraction and assess potential associations between these features and outcome of the procedure.

ANIMALS

74 horses and 7 ponies.

PROCEDURES

Medical records were searched to identify horses and ponies that underwent CT and intraoral extraction of ≥ 1 cheek tooth with standing sedation. Signalment and clinical variables were recorded, and CT scans were reviewed. Anatomic location and measurements of affected teeth; abnormalities of the periodontium, pulp, infundibula, roots, and tooth shape; fracture presence and type; presence of sinusitis; and affected sinus cavities were assessed by a surgeon and a radiologist. Intraoral extraction outcome was recorded as successful (complete removal of the tooth in 1 intraoral extraction procedure) or unsuccessful. Univariable and multivariable logistic regression analyses were performed to assess associations between clinical or CT findings and outcome.

RESULTS

89 cheek teeth (80 maxillary and 9 mandibular) were included in the analyses. Sixty of 89 (67%) cheek teeth were extracted successfully (56/80 [70%] maxillary and 4/9 [44%] mandibular cheek teeth). Only presence of a simple fracture (vs no fracture) was associated with outcome on multivariable regression analysis; odds of successful intraoral extraction were significantly lower when this feature was present.

CONCLUSIONS AND CLINICAL RELEVANCE

Most extractions of cheek teeth in the study sample were successful, and results may be useful for practitioners in refining cheek tooth extraction plans for horses and ponies. Further studies are required to assess whether specific CT findings can be used to predict the outcome of intraoral extraction in equids.

Occlusal fissures in equine cheek teeth: μCT and histological findings

Fissures on the occlusal surface of equine cheek teeth are commonly encountered during oral examination. Generally, their presence is considered abnormal but their aetiopathogenesis and clinical impact on pulp disease is still undetermined. The aims of this research were to study the extent of occlusal cheek teeth fissures using high-resolution X-ray computed tomography (μCT) imaging and their histological characteristics. Twenty-seven teeth (of 15 horses) were scanned using μCT imaging to analyse fissure extent. Histological examination of a subset of teeth (n=7) was performed. Forty-three type 1 fissures (35 type 1a, eight type 1b) were identified. The mean length of the fissure of type 1a and type 1b on the occlusal surface was 3.47+/-1.60mm and 13.64+/-7.40mm, respectively. Their mean depth was 13.22+/-10.76mm and 7.42+/-6.42mm, respectively. Potential risk factors associated with fissure depth were identified using a multivariable mixed model The location of the fissure and Triadan number were significantly associated with fissure depth. Fissures could be identified on histological sections with the presence of organic material inside the fissure, microorganisms in the continuation of the fissure extending into the dentinal tubules and the presence of reactionary dentine. This study suggests that fissures can provide a pathway for microorganisms to enter the dentinal tubules, potentially resulting in local pulpal inflammation. It appears that in healthy teeth, vital odontoblasts react by producing reactionary (tertiary) dentin, which lacks patent tubules and thus provides a proper seal.

Successful Treatment of a Persistent Oroantral Fistula via Transbuccal and Transnasal Endoscopic Debridement in a Horse

We report an unusual case of a young Quarter Horse with a large dental fracture fragment displaced into the maxillary sinus, leaving an oroantral communication that caused food impaction and metaplastic calcification in the sinus and facial deformation with cutaneous fistulation. Oral extraction of a remaining tooth fragment from its alveolus was succeeded by a maxillary sinusotomy for removal of the abnormal sinus contents. Since the oroantral fistula did not heal spontaneously following the placement of a silicone dental prosthesis, minimally invasive transbuccal and transnasal endoscopic approaches were used to encourage closure of the oroantral fistula by alveolar granulation. The clinical, diagnostic, and therapeutic features of this case may be helpful to clinicians when dealing with similar cases.

Equine cheek tooth extraction: Comparison of outcomes for five extraction methods

BACKGROUND

Post-operative complications are reported for all methods of equine cheek tooth extraction but not all methods carry the same risks. An outcome comparison for commonly used methods is needed so that clinicians can make informed treatment decisions.

OBJECTIVES

We conducted a side-by-side comparison of five cheek tooth extraction methods, comparing types and incidence of complications among oral extraction, tooth repulsion (three surgical approaches) and lateral buccotomy techniques.

STUDY DESIGN

Retrospective clinical study using hospital medical records.

METHODS

Medical records of all horses undergoing cheek tooth extraction between 1997 and 2013 were reviewed. Logistic regression was used to determine the likelihood of various post-operative complications, comparing oral extraction, tooth repulsion by maxillary and mandibular trephination or maxillary sinus bone flap, and lateral buccotomy.

RESULTS

The study included 137 horses and 162 cheek teeth extractions. Oral extraction was successful in 71% of patients in which it was attempted. Oral extraction (n = 55) had the lowest incidence of complications (20%) and repulsion by sinus bone flap (n = 20) the highest (80%). Complication rates for repulsion by maxillary (n = 19) and mandibular trephination (n = 28), and extraction by lateral buccotomy (n = 15) were 42, 54 and 53%, respectively. Cheek tooth repulsion by sinus bone flap significantly increased the odds of damage to adjacent teeth, post-operative sinusitis, damage to alveolar bone, delayed alveolar granulation and orosinus fistulation. Repulsion by maxillary trephination significantly increased the odds of superficial incisional surgical site infection; and extraction by lateral buccotomy significantly increased the odds of facial nerve neuropraxia. Post-operative pyrexia was more common in all repulsion methods.

MAIN LIMITATIONS

Some clinically relevant differences may have been missed due to small group numbers in several categories.

CONCLUSIONS

Oral extraction was associated with fewer post-operative complications than any other methods. Standing oral extraction remains the preferred choice, and recent surgical advances promise to further improve its success rate.

A new understanding of oral and dental pathology of the equine cheek teeth

Equine dental disease has a high prevalence. Because of developmental, functional, and anatomic differences, limited inference can be made from brachydont dental pathology to that of equine cheek teeth. This article reviews the pathology of equine cheek teeth and their associated oral tissues, with specific information on periodontitis, pulpitis, maxillary infundibular changes, dental fractures, dental overgrowths, mucosal ulceration, and the regenerative capacity of equine teeth.

Equine idiopathic cheek teeth fractures: Part 3: A hospital-based survey of 68 referred horses (1999-2005)

REASONS FOR PERFORMING STUDY

There is limited information available on the more serious sequellae of idiopathic cheek teeth (CT) fractures.

OBJECTIVES

To obtain information on clinical and ancillary diagnostic findings in referred horses with idiopathic CT fractures.

METHODS

Details of all horses suffering from idiopathic CT fractures referred to the Equine Hospital at the University of Edinburgh 1999-2005 were examined, and information concerning fracture patterns, clinical and ancillary diagnostic findings, treatments and long-term response to treatments were obtained and analysed.

RESULTS

A total of 60 maxillary and 17 mandibular idiopathic CT fractures were diagnosed in 68 horses. Fracture patterns included maxillary CT lateral slab fractures (45%), maxillary CT midline sagittal fractures (16%) and various other patterns of maxillary CT fractures (17%). In the mandibular CT, lateral slab fractures were found (12%) and various other CT fracture patterns were present in 10%. The more centrally positioned CT (maxillary and mandibular Triadan 08s and 09) were preferentially fractured. Clinical signs included quidding in 47% of cases; bitting and behavioural problems (28%); signs of apical infection, including bony swellings and nasal discharge (21%); anorexia/weight loss (15%); halitosis (13%); and buccal food impaction (12%). The treatment of all cases was conservative whenever possible and included corrective rasping of the remaining tooth (46% of cases); oral extraction of the smaller and loose dental fragment (32%) and extraction of the entire fractured tooth by oral extraction (28%) or by repulsion (13%). Prophylactic treatment of adjacent, nonfractured CT with carious infundibula was possibly of value in preventing further midline sagittal maxillary CT fractures.

CONCLUSIONS

Horses referred with idiopathic CT fractures frequently have clinical signs of apical infection of the fractured CT and these teeth require extraction, orally if possible. More conservative treatment of idiopathic CT fractures without signs of gross apical infection can resolve clinical signs in most cases.

POTENTIAL RELEVANCE

In the absence of apical infection, extraction of only the loose dental fragments of CT with idiopathic fractures is usually successful.

Equine idiopathic cheek teeth fractures. Part 1: Pathological studies on 35 fractured cheek teeth

REASONS FOR PERFORMING STUDY

There is little published information on the pathology of idiopathic fractures of cheek teeth (CT).

OBJECTIVES

To perform pathological examinations on equine CT with idiopathic fractures in order to establish fracture patterns and to gain information on their aetiopathogenesis.

HYPOTHESIS

Gross and histological examination of CT with idiopathic fractures, including measurements of dentinal thickness, will provide information on fracture patterns, and on the duration and aetiopathogenesis of these fractures.

METHODS

Of 35 CT with idiopathic fractures that were examined to determine their fracture patterns, 20 underwent gross, histological and ultrastructural examinations, including dentinal thickness measurements, with the latter compared to dentinal measurements of dental age and Triadan position matched control CT, to help determine the duration of any pre-existing endodontic disease.

RESULTS

The fracture planes involved the pulp chambers in 30 out of 35 CT examined, and ran through coalesced, carious infundibula in the other 5 (maxillary) CT. The maxillary CT, particularly the Triadan 09 position were preferentially affected. The most common fracture plane, which was termed a maxillary buccal slab fracture, occurred through the 2 lateral (1st and 2nd) pulp chambers of maxillary CT and usually involved only the clinical crown. Buccal slab fractures of mandibular CT (through 4th and 5th pulp chambers) and midline sagittal fractures through the infundibula (of maxillary CT) were the next most common fracture patterns. Reduced dentinal thickness (probably indicating prior pathological changes in the fractured CT) was present in 25% of fractured CT.

CONCLUSIONS

Most idiopathic equine CT fractures involve the pulp chambers, especially those on the buccal aspect of both upper and lower CT. No predisposition to fracture was found in the majority of affected CT that appeared to have a normal endodontic appearance prior to development of fractures through their pulp chambers. The remaining idiopathic CT fractures were caused by advanced infundibular caries.

POTENTIAL RELEVANCE

All CT with idiopathic fractures are all at risk of pulpar or even apical infection.